Preheat oven to 400°F. Prepare 2 baking sheets with parchment paper.
Sauté onion on medium heat for 3 minutes, add garlic. Remove from heat when garlic starts to brown.
1/4 white onion, 2 cloves garlic
Mix together onion mixture, spinach, artichokes, cheeses, red pepper flakes, salt and pepper.
10 ounces frozen spinach, 14 ounces artichoke hearts, 6 ounces gruyere, 1/4 cup feta, 1/2 teaspoon red pepper flakes, Salt + pepper
Lightly roll out one sheet of puff pastry on lightly floured surface. Fill using 1/2 of spinach filling, leaving 1/2" bare on long edge.
2 sheets pre-made puff pastry, defrosted
Roll into pinwheel shape starting on the non-bare long side of the rectangle. Seal using egg wash on bare edge.
Repeat with second sheet of puff pastry.
Egg wash sides and top of each pinwheel.
Egg wash
If dough warms while working, chill pans in fridge for 20 minutes before baking.
Bake for 30-35 minutes until golden brown.